[piolaxo]

Originally Posted by macman007

I have an off day tomorrow (Monday), so after I make progress on some customer stuff, finish and prepare to ship, I'm going to dig in and check the components you listed above. ON the -32 volt J1 : J12 , It reads -32vdc in the schematic, however I read 3.2vdc. I thought perhaps that 32vdc is a misprint and it was actually supposed to be 3.2vdc. Do we know for sure if it's 3.2 or 32 VDC?


I can't tell if the filament is intact or not,. However all lights out in the dark room, unit powered up, there is zero light emitting from anywhere on the VF display. The faceplate fiber optic/ led illumination is working 100%, as are all controls on the front. That was one of the things I first looked at initially, thinking the same thing.

I do need to clear up as to whether the J1 pin J12 is supposed to measure 3.2vdc or -32vdc. My brain is telling me there should also be +32vdc on another pin or +3.2vdc as well as -3.2/32vdc, measured to ground for the + and - voltage supply.

It would be odd for the actual voltage to spec at -32vdc and I measure 3.2vdc. Misprint perhaps? Do we know that it is 100% supposed to measure 32vdc? I had that thought when I first measured against the schematic specs, and it wouldn't be the first time a schematic was misprinted. I've been down similar alleys before with other gear, but I'd think a company prestigious and exacting as McIntosh would not make that type of published mistake.

You never know until you know.

My continued thanks to everyone for their help. I have no doubts that between us all, we'll get to the bottom of this and get her display up and running very soon!

Hi again, no it is not a misprint. It is -32V. If you search for OKI ML9207
5x7 Display Controller manual, you will find that the VFD supply ranges
from -20V to -60V. So -32V is right in the range.

You should check not only the regulators, but the diodes feeding the
regulators. It is a power supply issue for sure. The display should be okay.

Sal